BaTiO3-PbTiO3 series single crystal and method of manufacturing the same, piezoelectric type actuator and liquid discharge head using such piezoelectric type actuator

ABSTRACT

BaTiO 3 —PbTiO 3  series single crystal is single-crystallized by heating BaTiO 3 —PbTiO 3  compact powder member or sintered member having a smaller Pb-containing mol number than Ba-containing mol number, while keeping the powder or substance in non-molten condition. In this way, this single crystal can be manufactured at a crystal growing speed faster still and stabilized more, significantly contributing to improving the dielectric loss and electromechanical coupling coefficient for the provision of excellent BaTiO 3 —PbTiO 3  series single crystal in various properties, as well as for the provision of piezoelectric material having a small ratio of lead content, which is particularly excellent in piezoelectric property and productivity.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to the BaTiO₃—PbTiO₃ series singlecrystal that can be utilized as a piezoelectric element, for example,and also, relates to the method of manufacturing the same. Further, theinvention relates to a piezoelectric type actuator formed by theBaTiO₃—PbTiO₃ series single crystal, and the liquid discharge head thatuses such piezoelectric type actuator as well.

[0003] 2. Related Background Art

[0004] The BaTiO₃ series single crystal is a nonlinear optical crystalutilized for optical communications, information processing, or thelike, and having a great marketability, which is not only used as aphase conjugate wave generating medium for a high resolution imageprocessing, a real-time hologram, or a laser resonator, but also, usedas a highly capable piezoelectric material if the crystallizationthereof can be implemented at lower costs.

[0005] Now, obviously, the composition of the BaTiO₃ makes it difficultto obtain single crystal directly from the BaTiO₃ solution when BaTiO₃series single crystal is manufactured. Therefore, only the flux growththat uses solution (flux) having fluoride and chloride as main componentor the method, in which the BaTiO₃ series single crystal oflow-temperature component is picked up directly by making thecomposition of the solution TiO₂ rich (the so-called top seeded solutiongrowth (TSSG method)), is applicable to the growth thereof. With theflux growth, the obtainable size is only 1 mm³ or less approximately.Also, for the TSSG method, not only an expensive noble metal crucible,such as a platinum crucible, is needed, but the growing speed is slow tomake the manufacturing costs extremely high.

[0006] Conventionally, it has been attempted to provide a method formanufacturing larger BaTiO₃ series single crystal more effectively andeasily with the improvement of the aspects that present the problems asdescribed above.

[0007] For example, there are experiments carried out in manufacturingBaTiO₃ series single crystal efficiently by sintering method. In thespecifications of Japanese Patent Application Laid-Open Nos. 4-300296,5-155696 and 5-155697, a method for manufacturing BaTiO₃ series singlecrystal is disclosed, in which the BaTiO₃ series single crystal servingas the seed crystal is coupled with the BaTiO₃ polycrystal, and heatedto mono-crystalize such polycrystal by means of solid-phase reaction. Inthe specification of Japanese Patent Application Laid-Open No. 9-263496,a method for manufacturing BaTiO₃ series single crystal is disclosed, inwhich a temperature gradient is given to the BaTiO₃ micro-crystalgranular aggregate, the mol ratio of Ti/Ba of which is 1.0 or more and1.1 or less, for the execution of single crystallization thereof. Withthese methods, however, the mono-crystalline growth rate greatly variesto make it impossible to grow any bulky single crystal with goodreproducibility. Also, the rearrangement density is high, and thecrystallinity of the BaTiO₃ series single crystal thus obtained isinferior to the one obtained by the conventional TSSG method and theflux method. There are also the examples of solid-phase methods otherthan the sintering method. In the specification of Japanese PatentApplication Laid-Open No. 59-3091, there is the disclosure of a methodfor manufacturing the oxide single crystal, in which a crystal oxide,such as PbTiO₃, BaTiO₃, SrTiO₃, CaTiO₃, is quenched and solidified aftermolten to make it amorphous, and then, re-crystallized under atemperature gradient. This method makes the manufacturing apparatus andprocess complicated, because there is a need for a process to melt thecrystal oxide. Also, the single crystal thus obtained has inferiorcrystallization properties, and only the crystal that has a high ratioof pore content is obtainable eventually.

[0008] Also, improvement studies have been made on the TSSG method andthe flux method. In the specification of Japanese Patent ApplicationLaid-Open No. 6-321698, there is disclosed, as the flux method, a methodfor manufacturing BaTiO₃ using a mixed substance of BaF₂, NaF, Li₂MoO₄,or the like as flux. In this method, the solubility of BaTiO₃ isenhanced for the purpose of obtaining bulky BaTiO₃ series single crystalwith a long-time crystal growth. However, this method is not fullysatisfactory in terms of the time required for manufacturing and costs.In the specification of Japanese Patent Application Laid-Open No.9-59096, there is disclosed BaTiO₃ series single crystal having thedoping of fine quantities of Mg and Fe. This material aims at obtaininga high photo-refractivity in the near infrared range, but Mg, Fe, orsome other element, which may exert unfavorable influence on thepiezoelectric property, is contained in that material. As a result, itis not preferable to use this as a piezoelectric material. Also, for theutilization at the industrial level, it is not satisfactory in terms ofthe time required for manufacture and costs.

[0009] As described above, the TSSG or flux method for manufacturingBaTiO₃ series single crystal makes it extremely difficult to improveproblems related to manufacturing efficiency, such as the time requiredfor manufacturing and costs, among some others. Here, although thesintering method is anticipated to enhance the manufacturing efficiency,the variation of growing speed of BaTiO₃ series single crystal makes itimpossible to obtain any satisfactory result, and also, thecrystallinity of the BaTiO₃ series single crystal thus obtained isinferior to the one obtainable by means of TSSG or flux method. In otherwords, it has been difficult to implement the manufacture of BaTiO₃series single crystal having excellent crystallinity and property in ashorter period of time at lower costs.

SUMMARY OF THE INVENTION

[0010] For the formation of BaTiO₃ series single crystal by sinteringmethod, the inventors hereof have attempted to make the enhancement ofthe reproducibility of single crystal growth compatible with theenhancement of crystallinity and other substances by adding othercomponent to BaTiO₃ itself. With this in view, the inventors hereof havestudied assiduously, with the result that a system, in which PbTiO₃ isadded to BaTiO₃, is found to enable a crystallization growth to occurwith an extremely fine reproducibility, satisfied only with apredetermined condition. Therefore, the studies have been made furtherin detail on the BaTiO₃—PbTiO₃ system to design the present inventioncompletely.

[0011] The inventors hereof have measured the crystallinity of theBaTiO₃—PbTiO₃ series single crystal obtained in accordance with thepresent invention. As a result, it is found that the BaTiO₃—PbTiO₃ ofthe present invention is extremely fine in the crystallinity thereof. Itis also confirmed by the X-ray diffraction and electron beam diffractionthat the crystal orientation of the single crystal is completelycoincident. Also, by the observation of etch pit, which will bedescribed later, it is confirmed that the rearrangement density of thecrystal is low, and that from this observation, the excellent crystalhas a small amount of lattice defect. The ratio of pore content is alsoextremely small.

[0012] Following this, the other properties of the BaTiO₃—PbTiO₃ seriessingle crystal, such as permittivity, piezoelectric property, andpyroelectric property, among some others, are examined. As a result, itis found that the piezoelectric property is excellent in particular,which is far superior to the property of PZT (Pb (Ti, Zr) O₃)polycrystal currently used as standards, or that of BaTiO₃ series singlecrystal manufactured by means of the TSSG method, not to mention that ofBaTiO₃ polycrystal.

[0013] From the viewpoint of the BaTiO₃—PbTiO₃ series single crystal asa piezoelectric material, it has such advantages as the wide range oftemperatures at which it can be used, and the lower amount of leadcontent that it has attained, as well as the excellent piezoelectricproperty that it can provide. The curie temperature of BaTiO₃ seriessingle crystal is approximately 120° C. (T_(c)). Any element that usesthe BaTiO₃ series single crystal has a narrow usable temperature rangedue to low T_(c) as practical drawbacks. The BaTiO₃—PbTiO₃ series singlecrystal of the present invention has a higher curie temperature (T_(c))than the aforesaid BaTiO₃ polycrystal to make it possible to make therange of usable temperature larger.

[0014] Also, in order to reduce the load to the environment on earth, itis required to reduce the amount of lead to be used for any industrialproduct in recent years. As compared with the PZT polycrystal, whichpresents the main current of piezoelectric material at present, theBaTiO₃—PbTiO₃ series single crystal of the present invention is found tobe able to reduce the use amount of lead significantly owing to thecomposition that is different therefrom, and further, to enhance thepiezoelectric property conspicuously. Also, it has been found that theuse amount of piezoelectric material itself, which is needed forproducing the same effect, is reduced significantly. At present, it isconsidered to use BaTiO₃ polycrystal, Bi_(0.5)Na_(0.5)TiO₃ series singlecrystal (Na_(0.5)K_(0.5)) NbO₃ polycrystal as a promising material forsubstitution of PZT for the purpose of reducing the lead use amount.However, against the PZT piezoelectric constant d₃₃=300 to 400 (×10⁻¹²C/N) and electromechanical coupling coefficient k₃₃=0.6 to 0.7, theBaTiO₃ polycrystal has the piezoelectric constant d₃₃=120 (×10⁻¹² C/N)and electromechanical coupling coefficient k₃₃=0.4 to 0.5, and theBi_(0.5)Na_(0.5)TiO₃ has the piezoelectric constant d₃₃=110 (×10⁻¹² C/N)and electromechanical coupling coefficient k₃₃=0.4 to 0.6. Therefore,the piezoelectric property is not satisfactory.

[0015] Also, the piezoelectric property of the BaTiO₃—PbTiO₃ polycrystalis far inferior in terms of a piezoelectric material to that of the PZTpolycrystal or the BaTiO₃—PbTiO₃ series single crystal, and there is noway fundamentally to enhance the piezoelectric property as singlecrystal. It is also considered more difficult to manufactureBaTiO₃—PbTiO₃ series single crystal by the method other than the onedesigned by the present invention, such as the flux method, the TSSGmethod, or any other melt-solidification method than to manufactureBaTiO₃ series single crystal. There is no value that can be found inthese methods. As described earlier, regarding the BaTiO₃ series singlecrystal, only the small one, the size of which is approximately 1 mm³ orless, is obtainable by means of the flux method. Also, for the TSSGmethod, an expensive noble crucible, such a platinum crucible, isneeded. In addition, the growing speed is only 0.1 to 0.2 mm/happroximately, leading to an extremely high cost of manufacture.Further, the material loss is great, and there is a drawback that it isdifficult to obtain bulky crystal. Such an extremely high cost ofmanufacture is inevitable to make the field of utilization thereofextremely limited. It has been pointed out that this is valueless as amaterial of industrial use. On the functional aspect, too, impuritiestend to be mixed during the single crystal growing process. There areoften the cases where the anticipated performance cannot be demonstratedafter all. It is also anticipated that there is the same problemregarding the BaTiO₃—PbTiO₃ series single crystal if it should bemanufactured using the melt-solidification method.

[0016] As the example of a method for manufacturing perovskite oxidesingle crystal, there is the discloser in the specification of JapanesePatent Application Laid-Open No. 9-188597, in which a process isprovided for enabling the perovskite sintered member of Pb{(Mg_(1/3)Nb_(2/3))_(1-x)Ti_(x)} O₃ (in the aforesaid compositionformula, 0≦x≦0.55. Pb of 10 mol % or less may be replaced with Ba, Sr,Ca, or the like) to be in contact with seed crystal, and heated at atemperature of 1,000 to 1,450° C. in the closed container in the leadatmosphere. However, there is no disclosure of the BaTiO₃—PbTiO₃ seriessingle crystal having a smaller mol number of Pb than that of Ba. Thereis also no disclosure as to the effect thereof as a matter of course.Also, when the ratio between the A site and B site of the aforesaidperovskite sintered member is 1.00>A/B, the crystallization speed isremarkably slow. This is the tendency that differs from the presentinvention as described later.

[0017] It is an object of the present invention to improve thedielectric loss and electromechanical coupling coefficient, and provideexcellent BaTiO₃—PbTiO₃ series single crystal in various properties,such as permittivity, piezoelectric property, pyroelectric property, andalso, to provide BaTiO₃—PbTiO₃ series single crystal as thepiezoelectric material having a small ratio of lead content, which isparticularly excellent in piezoelectric property and productivity. It isanother object of the invention to provide a method for manufacturingBaTiO₃—PbTiO₃ series single crystal capable of manufacturingBaTiO₃—PbTiO₃ series single crystal efficiently, not by means of thesingle crystal growth using the melt-solidification method. It is stillanother object of the invention to provide a piezoelectric type actuatorusing the BaTiO₃—PbTiO₃ series single crystal, and a liquid dischargehead as well.

[0018] The BaTiO₃—PbTiO₃ series single crystal of the present inventionis single-crystallized by heating BaTiO₃—PbTiO₃ compact powder member orsintered member having a smaller Pb-containing mol number thanBa-containing mol number, while keeping the powder or member innon-molten condition. The inventors hereof have found that it becomespossible for the conventional manufacture of BaTiO₃ series singlecrystal by means of the sintering method, which is unable to grow singlecrystal with good reproducibility, to perform a stable single crystalgrowth by adding PbTiO₃ to BaTiO₃ so that the Pb-containing mol numberis made smaller than the Ba-containing mol number, hence designing thepresent invention completely.

[0019] It is preferable for the BaTiO₃—PbTiO₃ series single crystal ofthe invention that the rearrangement density is 10² pieces/cm² or moreand 10⁶ pieces/ m² or less, and the ratio of pore content is within arange of 1 volume ppm or more and 5 volume % or less. In this way, theBaTiO₃—PbTiO₃ series single crystal of the invention makes thedielectric loss smaller, and the electromechanical coupling coefficientlarger. For example, the dielectric loss is 1% or less, and theelectromechanical coupling coefficients exceeds 85%.

[0020] It is preferable for the BaTiO₃—PbTiO₃ series single crystal ofthe invention that the ratio of PbTiO₃ content is 45 mol % or less inthe BaTiO₃—PbTiO₃ series single crystal. When the ratio of PbTiO₃content in the BaTiO₃—PbTiO₃ compact powder member or sintered member,which serves as the starting substance, is arranged to be 45 mol % orless, the single crystal growing speed is promoted more to make itpossible to manufacture the single crystal substance more stably. Then,the resultant ratio of PbTiO₃ content in the BaTiO₃—PbTiO₃ series singlecrystal is the same as the ratio of PbTiO₃ content in the startingsubstance. It is preferable for the BaTiO₃—PbTiO₃ series single crystalof the invention that the ratio of PbTiO₃ content is 30 mol % or less,and more preferably, it is 25 mol % or less. If the ratio of PbTiO₃content is too much, the evaporation of Pb becomes conspicuous, andcomposition changes from the target one, while the single crystal thusobtained tends to become porous. In order to suppress the Pbevaporation, it is imperative that a pressurized container be utilized,presenting a disadvantage that the manufacturing costs become higher.Also, the minimum amount of PbTiO₃ content in the BaTiO₃—PbTiO₃ seriessingle crystal of the invention should preferably be 0.01 mol % or more,and more preferably, it is 0.02 mol % or more.

[0021] It is preferable for the BaTiO₃—PbTiO₃ series single crystal ofthe invention that the volume of the single crystal is 1 mm³ or more.The volume of the BaTiO₃—PbTiO₃ series single crystal of the inventioncan easily be made 1 mm³ or more with the stable crystal growth. Withthe volume of 1 mm³ or more, the single crystal makes it possible tofavorably deal with many devices in various sizes due to the area thatcan be made larger. Also, according to another mode of the presentinvention, the BaTiO₃—PbTiO₃ series single crystal is characterized inthat the rearrangement density of 10² pieces/cm² or more and 10⁶pieces/cm² or less, and the ratio of pore content being within in arange of 1 volume ppm or more and 5 volume % or less. More preferably,the ratio of PbTiO₃ content is 45 mol % or less for the BaTiO₃—PbTiO₃series single crystal of the invention. In this way, the BaTiO₃—PbTiO₃series single crystal of the invention makes the dielectric losssmaller, and the electromechanical coupling coefficient larger.

[0022] Also, the method of the present invention t,or manufacturingBaTiO₃—PbTiO₃ series single crystal comprises the step ofsingle-crystallizing BaTiO₃—PbTiO₃ compact powder member or sinteredmember having a smaller Pb-containing mol number than Ba-containing molnumber by defining the range of the mol ratio of elements containedtherein to be 0.9800<(Ba+Pb)/Ti<1.0000, and by heating, while keepingthe powder or substance in non-molten condition. More preferably, therange of the mol ratio of elements contained in the compact powdermember or sintered member is defined to be 0.9900<(Ba+Pb)/Ti<1.0000.Still more preferably, the range of the mol ratio of elements containedin the compact powder member or sintered member is defined to be0.9950≦(Ba+Pb)/Ti≦0.9999. By heating the BaTiO₃—PbTiO₃ compact powdermember or sintered member having a smaller Pb-containing mol number thanBa-containing mol number, while keeping it in non-molten condition, thereproducibility of single crystal growth is enhanced as compared withthe same process of only the BaTiO₃ compact powder member or sinteredmember that does not contain PbTiO₃, thus making it possible tomanufacture the stable BaTiO₃—PbTiO₃ series single crystal. Further, bydefining the mol ratio of elements contained in the BaTiO₃—PbTiO₃ seriessingle crystal within a specific range, the crystal growing speed ofBaTiO₃—PbTiO₃ series single crystal becomes faster.

[0023] It is preferable for the method of the present invention formanufacturing BaTiO₃—PbTiO₃ series single crystal that the ratio ofPbTiO₃ content is 45 mol % or less in the BaTiO₃—PbTiO₃ compact powdermember or sintered member. When the ratio of PbTiO₃ content in theBaTiO₃—PbTiO₃ compact powder member or sintered member, which serves asthe starting substance, is arranged to be 45 mol % or less, the singlecrystal growing speed is promoted more to make it possible tomanufacture the single crystal substance more stably. It is preferablefor the method of the invention for manufacturing BaTiO₃—PbTiO₃ seriessingle crystal that the ratio of PbTiO₃ content in the BaTiO₃—PbTiO₃series single crystal compact powder or sintered member is 30 mol % orless, and more preferably, it is 25 mol % or less. If the ratio ofPbTiO₃ content is too much, the evaporation of Pb becomes conspicuous,and composition changes from the target one, while the single crystalthus obtained tends to become porous. In order to suppress the Pbevaporation, it is imperative that a pressurized container be utilized,presenting a disadvantage that the manufacturing costs become higher.Also, in the method for manufacturing BaTiO₃—PbTiO₃ series singlecrystal, the minimum amount of PbTiO₃ content in the BaTiO₃—PbTiO₃compact powder member or sintered member should preferably be 0.01 mol %or more, and more preferably, it is 0.02 mol % or more.

[0024] It is preferable for the method of the present invention formanufacturing BaTiO₃—PbTiO₃ series single crystal to comprise the stepof single-crystallizing by heating the BaTiO₃—PbTiO₃ compact powdermember or sintered member within a temperature range of 1,200° C. ormore and 1,400° C. or less. By heating the BaTiO₃—PbTiO₃ compact powdermember or sintered member within a range of designated temperatures, thecrystal growing speed of BaTiO₃—PbTiO₃ series single crystal becomesfaster.

[0025] Further, the method of the present invention for manufacturingBaTiO₃—PbTiO₃ series single crystal comprises the steps of preparingBaTiO₃ series single crystal or BaTiO₃—PbTiO₃ series single crystal asseed crystal; coupling BaTiO₃—PbTiO₃ series sintered member composed ofcrystal grain of average granular diameter of 20 μm or less, having therelative density of 95% or more, with the {100} plane, {110} plane, or{111} plane of the seed crystal; and single-crystallizing by heating,while keeping the coupled substance in non-molten condition. Morepreferably, the mol ratio of elements contained in the BaTiO₃—PbTiO₃compact powder member or sintered member is within a range of0.9950≦(Ba+Pb)/Ti≦0.9999. In the method of the invention formanufacturing BaTiO₃—PbTiO₃ series single crystal, the singlecrystallization takes place stably form the coupling portion between thecompact powder member or sintered member and the seed crystal by use ofthe BaTiO₃—PbTiO₃ compact powder member or sintered member coupled withthe seed crystal in the aforesaid condition, and the reproducibility ofsingle crystal growth is enhanced. Also, if the mol ratio of elementscontained in the aforesaid compact powder or sintered member is withinthe designated range, the crystal growing speed of BaTiO₃—PbTiO₃ seriessingle crystal becomes faster still.

[0026] It is preferable for the method of the present invention formanufacturing BaTiO₃—PbTiO₃ series single crystal to comprise the stepof single-crystallizing by heating, while keeping the compact powdermember or sintered member in the lead atmosphere and in non-moltencondition. As one of the methods for forming the lead atmosphere, it ispossible to evaporate lead or lead oxide form the lead-containedcompound by enabling the lead-contained compound to coexist in theenvironment in which the BaTiO₃—PbTiO₃ compact powder member or sinteredmember is heated, while being kept in non-molten condition. By heatingthe BaTiO₃—PbTiO₃ compact powder member or sintered member in the leadatmosphere, it becomes possible to prevent lead, lead oxide, or the likefrom being evaporated from the BaTiO₃—PbTiO₃ compact powder member orsintered member or the BaTiO₃—PbTiO₃, series single crystal. In thisway, the increase of rearrangement density and the ratio of pore contentin the BaTiO₃—PbTiO₃ series single crystal can be suppressed, thusmaking it possible to manufacture high quality BaTiO₃—PbTiO₃ seriessingle crystal.

[0027] Further, the piezoelectric type actuator of the present inventioncomprises a layer formed by BaTiO₃—PbTiO₃ series single crystaldescribed earlier. Also, the liquid discharge head of the presentinvention comprises the aforesaid piezoelectric type actuator. Here, thepiezoelectric type actuator and liquid discharge head of the presentinvention use the BaTiO₃—PbTiO₃ series single crystal that has highelectromechanical coupling coefficient, high piezoelectric constant, andhigh curie temperature altogether as the piezoelectric material. Thus,the piezoelectric actuator and liquid discharge head can be materializedto provide high output with a wide range of usable temperatures. Also,from the viewpoint of the environmental improvement on earth, it ispreferable to use the aforesaid actuator and head, because the amount oflead contented in them is small.

[0028] The BaTiO₃—PbTiO₃ series single crystal of the present inventionis single-crystallized by heating BaTiO₃—PbTiO₃ compact powder member orsintered member having a smaller Pb-containing mol number thanBa-containing mol number, while keeping the powder or substance innon-molten condition. The effect of the reproducibility of the crystalgrowth of the present invention cannot be demonstrated even if themethod of manufacture thereof is applied to the compact powder member orsintered member composed of only BaTiO₃. Although the mechanism thereofhas not been confirmed as yet, it is inferred as given below. When theBaTiO₃—PbTiO₃ compact powder member or sintered member is heated, whilekept in non-molten condition, lead or lead compound is evaporated fromthe surface of the powder or signatured substance, and externallydispersed, and the deficiency of lead ensues on the surface of thecompact powder member or sintered member. Thus, lead shifts from theinside of the compact powder member or sintered member to the surface tocompensate for the deficiency thereof. At this juncture, the granularinterface in the inside the compact powder member or sintered membertends to move easily, hence enabling the crystal growth to occur stably.

[0029] The BaTiO₃—PbTiO₃ series single crystal of the present inventioncan be manufactured at a crystal growing speed faster still by preparingthe BaTiO₃—PbTiO₃ compact powder member or sintered member, which servesas starting substance, with a designated composition as describedearlier or by heating it within a designated range of temperatures. TheBaTiO₃—PbTiO₃ series single crystal of the present invention can bemanufactured with a crystal growing speed stabilized more by coupling adesignated single crystal as a seed crystal with the BaTiO₃—PbTiO₃compact powder member or sintered member, which serves as startingsubstance. FIGS. 2A to 2D are views that illustrate the state of thecrystal growth when the BaTiO₃—PbTiO₃ series single crystal of thepresent invention is manufactured, in which the designated singlecrystal 22 is coupled with the BaTiO₃—PbTiO₃ compact powder member orsintered member 24, and heated in non-molten condition. As shown in FIG.2B, it is understandable that on the coupling portion of theBaTiO₃—PbTiO₃ compact powder member or sintered member with the seedcrystal, particularly on the circumferential area thereof, the crystalgrowth occurs conspicuously. Conceivably, this is because the shift oflead occurs intensively particularly on the aforesaid circumferentialarea, and also, conceivably, this is the phenomenon that supports theaforesaid mechanism of crystal growth. Typically, in FIG. 2C, areference numeral 26 designates the single-crystallized portion, and 28,the polycrystal portion.

[0030] In accordance with the present invention, it is possible toprovide the BaTiO₃—PbTiO₃ series single crystal having the propertycomparable to the PZT material already made available as a Pb-less,piezoelectric material that serves the purpose of reducing the harmfulsubstance, such as Pb in PZT, among some others. Also, along with theincreased amount of Pb-containing, the curie temperature becomes higher,but it is possible to select the curie temperature up to approximately300° C. appropriately, thus presenting no problem as to the curietemperature. Also, the BaTiO₃—PbTiO₃ series single crystal manufacturedby the sintering method has a smaller dielectric loss, and the amount ofinductive distortion increases at the time of electric field applicationdue to significant rising of electromechanical coupling coefficientalong with the extinction of granular boundaries of the largelyoblique-angled ones, hence presenting extremely favorable piezoelectricproperty.

[0031] Further, in accordance with the method of manufacture of thepresent invention, it is possible to obtain high quality BaTiO₃—PbTiO₃series single crystal by preparing the seed crystal having bulky grainformed by sintering compact powder member, the specific compositionrange of which is (Ba+Pb)/Ti ratio, or by preparing the seed crystal bymeans of the conventional melt-solidification method, and also,producing the BaTiO₃—PbTiO₃ series sintered member, which is given thesame composition adjustment, and then, by giving heat treatmentsubsequent to the coupling of the seed crystal and the sintered member.The growing speed of single crystal by means of this sintering method iscomparable to that of the Melt-Growth method or superior thereto, andthe property of this single crystal is far superior to that of the PZTsintered member currently available.

[0032] Also, it is possible to process many numbers of samples bysintering method at a time, thus not only contributing to reducing theproduction cost significantly, but also, making the productivity and themaintenance of property compatible so as to keep the rearrangementdensity in crystal in an extremely small amount, and attain the highquality thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1A is a perspective view that shows a liquid discharge headin accordance with the present invention. FIG. 1B is a cross-sectionalview taken along line 1B-1B in FIG. 1A.

[0034]FIGS. 2A, 2B, 2C and 2D are the views of process flow thatillustrate one example of the method for manufacturing BaTiO₃—PbTiO₃series single crystal in accordance with the present invention.

[0035]FIG. 3 is a view that shows the X-ray diffraction pattern of theBaTiO₃—PbTiO₃ series single crystal of the present invention aftersingle crystallization by coupling seed crystals in accordance with aneleventh embodiment.

[0036]FIG. 4 is a view that shows the X-ray diffraction pattern of theBaTiO₃—PbTiO₃ series single crystal of the present invention aftersingle crystallization by coupling seed crystals in accordance with theeleventh embodiment.

[0037]FIG. 5 is a view that shows the electron diffraction pattern ofthe BaTiO₃—PbTiO₃ series single crystal of the present invention aftersingle crystallization using seed crystals in accordance with theeleventh embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The BaTiO₃—PbTiO₃ series single crystal of the present inventionis such that the BaTiO₃—PbTiO₃ compact powder member or sintered member,the mol number of Pb-containing of which is smaller than that of Ba, isheated and retained in non-molten condition for the singlecrystallization. Further, it is preferable for the BaTiO₃—PbTiO₃ seriessingle crystal of the present invention to mono-crystallize theBaTiO₃—PbTiO₃ compact powder member or sintered member by heating andretaining in the non-molten condition, with the mol ratio of elementscontained in them being arranged to be within a range of0.9800<(Ba+Pb)/Ti<1.0000. It is more preferable to keep the mol ratio ofelements contained in the compact power or sintered member within arange of 0.9900<(Ba+Pb)/Ti<1.0000. Still more preferably, the ratioshould be kept within a range of 0.9950≦(Ba+Pb)/Ti≦0.9999.

[0039] For the BaTiO₃—PbTiO₃ series single crystal of the presentinvention, it is preferable to arrange the content ratio of PbTiO₃ ofthe BaTiO₃—PbTiO₃ compact powder member or sintered member, which is thestarting substance thereof, to be 45 mol % or less. When the ratio ofPbTiO₃ content of the aforesaid compact powder member or sintered memberis arranged to be 45 mol % or less, the growing speed of single crystalis promoted, while the single crystal substance is produced more stably.The resultant composition of BaTiO₃—PbTiO₃ series single crystal thusobtained is almost the same as that of the starting BaTiO₃—PbTiO₃compact powder member or sintered member. Here, it is more preferable toarrange the amount of PbTiO₃ content to be 30 mol % or less or stillmore preferable to arrange it to be 25 mol % or less. If the amount ofPbTiO₃ content is too much, the evaporation of lead becomes conspicuousfrom the BaTiO₃—PbTiO₃ compact powder member, sintered member, or singlecrystal. Consequently, the obtainable composition of the BaTiO₃—PbTiO₃series single crystal is caused to change, and deviated from the targetcomposition. Further, the obtained BaTiO₃—PbTiO₃ series single crystalbecomes porous easily. In order to suppress the lead evaporation, it isimperative that a pressurized container be used, which leads to such anunfavorable problem of increased cost of manufacture. Also, the minimumamount of PbTiO₃ content of the BaTiO₃—PbTiO₃ compact powder member orsintered member should preferably be 0.01 mol % or more or, morepreferably, 0.02 mol % or more. The BaTiO₃—PbTiO₃ series single crystalof the present invention is single-crystallized by heating theBaTiO₃—PbTiO₃ compact powder member or sintered member within apreferable temperature range of 1,200° C. or more and 1,400° C. or less.The BaTiO₃—PbTiO₃ series single crystal of the present invention mayalso be single-crystallized by preparing another single crystal, such asBaTiO₃ series single crystal or BaTiO₃—PbTiO₃ series single crystal asseed crystal, and coupling this seed with the BaTiO₃—PbTiO₃ compactpowder member or sintered member, which is heated and retained. (If thecrystal construction is coincident, it is preferable that a latticeconstant and a thermal expansion coefficient of the polycrystal memberand seed crystal is within ±15%.) When using such seed crystal, itbecomes possible to match the crystal orientation of the BaTiO₃—PbTiO₃series single crystal with that of the seed crystal. Further, theBaTiO₃—PbTiO₃ series single crystal of the present invention is composedof the crystalline particles, the average granular diameter of which is20 μm or less, with the BaTiO₃ series single crystal or BaTiO₃—PbTiO₃series single crystal as seed crystal, and may be single-crystallized bycoupling the BaTiO₃—PbTiO₃ series sintered member having a relativedensity of 95% or more with the {100}, {110}, or {111} surface of theaforesaid seed crystal, which is heated and retained in non-moltencondition. Here, the BaTiO₃ series single crystal or BaTiO₃—PbTiO₃series single crystal used as the seed crystal is manufactured by themethod for manufacturing the BaTiO₃—PbTiO₃ series single crystal of thepresent invention or may be manufactured either by the general sinteringmethod or by the flux or TSSG method. Here, although the reasons are notclear, it is possible to manufacture excellent BaTiO₃—PbTiO₃ seriessingle crystal in a better quality when using the single crystal thathas been manufactured by the method of the present invention formanufacturing BaTiO₃—PbTiO₃ series single crystal as the seed crystalthan the single crystal manufactured by the flux or TSSG method. Themethod of the present invention for manufacturing BaTiO₃—PbTiO₃ seriessingle crystal includes a process in which BaTiO₃—PbTiO₃ compact powdermember or sintered member is single-crystallized by heating itpreferably in the lead atmosphere, and retained in non-molten condition.As a method for forming the lead atmosphere, a lead-contained compound,such as PZT or PbTiO₃, is arranged to be coexistent in the environmentwhere the BaTiO₃—PbTiO₃ compact powder member or sintered member isheated, and then, lead or lead oxide is evaporated from the aforesaidlead-contained compound. In this way, the composition changes of theBaTiO₃—PbTiO₃ series single crystal in the growing process(particularly, the lead evaporation from the BaTiO₃—PbTiO₃ series singlecrystal) can be suppressed, thus making it possible to increase thecrystallization speed more.

[0040] However, when manufacturing the BaTiO₃—PbTiO₃ series singlecrystal the ratio of PbTiO₃ content of which exceeds 30 mol %, the leadevaporation becomes particularly conspicuous to make it easier to changethe composition from the target one. Further, the ratio of pore contentof the obtained single crystal tends to become higher. In order tosuppress the lead evaporation, there are often the cases where only theexecution of the heating process under the lead atmosphere as describedearlier is not good enough. For example, it is preferable to execute theheating process in a pressurized container under a pressure of more thanone atmosphere. There is a need for a comparatively long period ofheating process (10 hours or more) when a single crystal synthesis isexecuted by the sintering method using such a pressurized container asHIP. As compared with the precess under the normal pressure, this isunfavorable in terms of the productivity and costs. For theBaTiO₃—PbTiO₃ series single crystal of the present invention, it isdesirable to provide the rearrangement density of 10² pieces/cm² or moreand 10⁶ pieces/cm² or less, and the ratio of pore content of 1 volumeppm or more and 5 volume % or less. In this way, the single crystal ofthe present invention presents a small dielectric loss, and a largeelectromechanical coupling coefficient. For example, the dielectric lossis 1 % or less, and the electromechanical coupling coefficient exceeds85 %.

[0041] Also, it is desirable for the BaTiO₃—PbTiO₃ series single crystalof the present invention to provide a volume of 1 mm³ or more. With thevolume of 1 mm³ or more, the crystal can be utilized for the varioussizes of many kinds of devices with the provision of a large areathereof, among some other means. Also, for the method of manufacture ofthe present invention, the material powder used for manufacturing theBaTiO₃—PbTiO₃ compact powder member or sintered member is notparticularly limited, and the following may be usable. In a case ofusing the solid-phase reaction, the following can be used:

[0042] 1) BaTiO₃ powder is produced by preliminarily sintering a mixtureof BaO (obtainable by thermal decomposition from BaCO₃ or bariumoxalate) and TiO₂, and PbTiO₃ powder is produced by preliminarilysintering a mixture of PbO and TiO₂; and further,

[0043] 2) The BaTiO₃—PbTiO₃ powder or the like, which is directlyproduced from BaO, PbO, and TiO₂ powder.

[0044] Also, it is possible to use the mixture of BaTiO₃ and PbTiO₃,which are obtainable by the wet or hydrothermal method, such ascoprecipitation or oxalic acid method, and also, BaTiO₃—PbTiO₃ powder orthe like, which is obtainable by the wet, hydrothermal method, such ascoprecipitation or oxalic acid method, among some others. For thematerial powder, it is desirable to keep the average granular diameterof the primary grain to be within a range of 0.055 μm. Also, asdescribed earlier, it is preferable to adjust the material powder sothat the mol ratio of the elements contained in the BaTiO₃—PbTiO₃compact powder member or sintered member, which is obtained from suchmaterial power to become the starting substance, should be0.9800<(Ba+Pb)/Ti<1.0000. Also, more preferably, the material powder isadjusted so that the mol ratio of the elements contained in theBaTiO₃—PbTiO₃ compact powder member or sintered member should be0.9900<(Ba+Pb)/Ti<1.0000. Still more preferably, it should be0.9950≦(Ba+Pb)/Ti<0.9999. The composition-adjusted powder is made to bethe compact powder member after the general formation by means of auniaxial press or a cold press using hydrostatic pressure. The compactpowder member, thus obtained may be made a sintered member by sinteringunder the normal condition. The compact powder member or sintered memberis heated in the non-molten condition to obtain the bulky crystal grainof the BaTiO₃—PbTiO₃ series single crystal having the average granulardiameter of 1 mm or more. The heating in the non-molten condition isgiven more preferably within a temperature range of 1,200° C. or moreand 1,400° C. or less. Further, using the single crystal thus obtainedby the aforesaid method as seed crystal it may become comparatively easyto make large BaTiO₃—PbTiO₃ series single crystal.

[0045] As described above, in order to make larger BaTiO₃—PbTiO₃ seriessingle crystal with ease, it is preferable to use some other singlecrystal as seed crystal. The seed crystal and the starting BaTiO₃—PbTiO₃compact powder member or sintered member are coupled, which is heatedand retained for crystallization. As a preferred seed crystal, BaTiO₃series single crystal or BaTiO₃—PbTiO₃ series single crystal is usablehere. As a preferred method for preparing the seed crystal, the methodof the present invention for manufacturing BaTiO₃—PbTiO₃ series singlecrystal, a general sintering method, or a melt solidification method,such as TSSG or flux method, is applicable here. Particularly, it ispreferable to use the single crystal prepared by the method of the,present invention for manufacturing BaTiO₃—PbTiO₃ series single crystalas the seed crystal, because the crystalline defect can be suppressedmore for the BaTiO₃—PbTiO₃ series single crystal thus obtained. The{100}, {110}, or {111} surface is cut out and polished to be thecoupling surface of the seed crystal.

[0046] Also, when the single crystallization is executed using the seedcrystal, the mol ratio of the elements contained in the BaTiO₃—PbTiO₃series sintered member to be single-crystallized should preferably beadjusted to be 0.9800<(Ba+Pb)/Ti<1.0000. More preferably, the mol ratioshould be adjusted to be 0.9900<(Ba+Pb)/Ti<1.0000. Still morepreferably, it should become 0.9950≦(Ba+Pb)/Ti≦0.9999. Further, thesintered member is sintered so that the average granular diameter of thecrystalline grain should be 20 μm or less, and the relative densityshould be 95% or more. The sintering method is not particularly limited,and the normally pressurized sintering, the hot press, the HIP (hotisostatic press), or the like is applicable here. In this respect, ifthe ratio of pore content of the sintered member exceed 5 volume %, theratio of pore content in the single crystal obtained by the crystalgrowth is also increased, which unfavorably lowers the mechanicalstrength thereof. With the composition having a large amount of lead inparticular, the ratio of pore content tends to become greater due to thelead evaporation during the growth of single crystal. In this case,therefore, it is preferable to keep the ratio of pore content in thesintered member to be less than 5 volume %. It is also preferable toprecisely polish the coupling surface of the sintered member and seedcrystal to be the surface roughness Ra=1.0 nm or less, and the flatnessλ (λ=633 nm) or less, respectively. The polished surfaces of thesintered member and seed crystal may be in contact directly or may be incontact after coating the organic or inorganic acid that contains Ba,Pb, Ti component. The seed crystal and sintered member, the polishedsurfaces of which are in contact with each other, should preferably becoupled by heating for a specific time with self-weight or a load ofapproximately 9.8 MPa or less. Further, it is more preferable to executethe coupling in the lead atmosphere in order to suppress the leadevaporation from neat the surface of sample in the coupling process.

[0047] For the purpose of promotion of crystal growth, a fine quantityof additives which is not replaceable or very difficult to be replacedwith A and B sites is added to the BaTiO₃—PbTiO₃ series single crystalof the present invention, the A site or B site of perovskite ABO₃structure is replaced with some other element, or a third component ofother perovskite structure may be given solid solution for the purposeof site exchange. The quantity thereof is not particularly limited, butpreferably, it is 10 weight percent or less for the fine amount ofadditives; 10 mol percent or less for each cyto as the element to bereplaced with the A cyto or B cyto; or 10 mol percent or less for allthe components as the third component to be given solid solution. Thekind of the component is not particularly limited, but preferably, it issuch element (ion) as Na, K, Ca, Cr, Co, Bi, Sr, La, Zr, Sn, Mg, Mn, Zn,Nb, Ta, Ni or the oxide or compound oxide that contains these elements.An extreme part of impurity components for promoting crystal growthresides in the single crystal as impurities in association with movementof the crystal growth border. However, there is no practical problemsince most of the components move to a distal end of the grown crystal.

[0048] Now, the element analysis of Ba, Pb, Ti, or the like for thecompact powder member, sintered member, or single crystal can be made byuse of an analyzer dedicated therefor in accordance with the analyticalmethod, such as fluorescent X-ray analysis, ICP (emission plasma)analysis, or ICP-MASS (emission plasma-mass) analysis, among someothers. Also, the crystallinity and orientation of single crystal can beconfirmed by means of such method as etch-pit image observation, thein-plane measurement and out-of-plane measurement of X-ray diffraction,or electron diffraction measurement, among some others, which are usedfor the measurement of rearrangement density to be described later.

[0049] Regarding the ratio of pore content in the sintered member andthe grown single crystal, the porous amount (porous area) exposed on thesurface of a sample after the mirror surface polishing is measured byuse of a reflection microscope, SEM (scanning electron microscope), orthe like if the value thereof is approximately 0.1 volume % or more, andthen, the ratio of pore content is worked out by the ratio of suchamount to the measured area. Also, if the value is approximately lessthan 0.1 volume %, this method is not good enough in terms of precision.Therefore, a thin piece of approximately several tens μm thick isprepared, and the size of pore and the number thereof, which exist inthe observable sight of a transmission microscope, are measured, and theratio of pore content is worked out by the ratio thereof to the observedvolume.

[0050] Also, the rearrangement in single crystal can be observed using amicroscope or the like as etch pit (=rearangement) by corroding thecrystalline surface of the single crystal with HCl—HF solution or thelike. In detail, the number of rearrangement (etch pit) generated inseveral hundreds to thousand μm² is counted and the counted number ischanged to per 1 cm² in order to determine the rearrangement density.

[0051] Hereinafter, the present invention will be described further indetail in accordance with the specific embodiments. It is to beunderstood, however, the present invention is not limited to suchembodiments.

First Embodiment

[0052] TiO₂ (26.7557 g), PbO (0.7440 g), and BaCO₃ (65.1209 g) are wetblended, and after dried, tentatively burned at 1,100° C. for fivehours, and, while being crushed, formed into a disk (of 16 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9950. This powder is sintered at 1,360° C. for10 hours to obtain the sintered member. The sintered member thusobtained is composed of bulky crystal grain of average granular diameterof approximately 2.0 mm. The composition of the sintered member is:BaTiO₃ of 99.0 mol %-PbTiO₃ of 1.0 mol %. From this sintered member, thebulky crystal grain is drawn out as seed crystal, and the (100) plane ofthe crystal grain is cut out and finished with the surface roughnessRa=0.2 nm and the flatness λ/2. On the other hand, the same compound isformed into a disc of 10 mm diameter×15 mm thick, and sintered at 1,280°C. for three hours to obtain the sintered member of BaTiO₃ of 99.0 mol%-PbTiO₃ of 1.0 mol % in the relative density of 97.3%. The averagegranular diameter of the crystal grain that constitutes this sinteredmember is approximately 10 μm. The composition thereof is(Ba+Pb)/Ti=0.9950. The end face of this sintered member is likewisemirror finished to be the surface roughness Ra=0.2 nm and the flatnessλ/2. The polished surfaces of both seed crystal and sintered member arerinsed using acetone for mechanical coupling, and retained in the oxygenatmosphere at 1,360° C. for 40 hours, while keeping this state in thenon-molten condition, for the execution of single crystallization. Inthe process of the single crystal growth, a magnesia crucible is coveredover the sample to suppress the Pb evaporation. After the growingprocess, the single crystallization takes place from the surface coupledwith the single crystal to approximately 12 mm.

[0053] From this result, it has been found that the growing speed is 0.3mm/h, and that the growth is possible at a speed much faster than thegrowing speed of the conventional melt solidification method. Also, theratio of pore content is 0.9 volume % in the single crystal of BaTiO₃ of99.0 mol %-PbTiO₃ of 1.0 mol %, which is obtained by the sinteringmethod using the seed crystal, and the rearrangement density is found tobe 1×10³/cm² when examined by etching it in the HCl—HF solution.

Second Embodiment

[0054] TiO₂ (26.64868 g), PbO (5.2080 g), and BaCO₃ (61.1742 g) are wetblended, and after dried, tentatively burned at 1,150° C. for fivehours, and, while being crushed, formed into a disc (of 20 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9990. This powder is sintered at 1,350° C. for10 hours to obtain the sintered member. The sintered member thusobtained is composed of bulky crystal grain of average granular diameterof approximately 3.0 mm. The composition of the sintered member is:BaTiO₃ of 93.0 mol %-PbTiO₃ of 7.0 mol %. From this sintered member, thebulky crystal grain is drawn out as seed crystal, and the (110) plane ofthe crystal grain is cut out and finished with the surface roughnessRa=0.3 nm and the flatness λ/4. On the other hand, the same compound isformed into a disc of 10 mm diameter×20 mm thick, and sintered at 1,250°C. for three hours to obtain the sintered member of BaTiO₃ of 93.0 mol%-PbTiO₃ of 7.0 mol % in the relative density of 99.1%. The averagegranular diameter of the crystal grain that constitutes this sinteredmember is approximately 8 μm. The composition thereof is(Ba+Pb)/Ti=0.9990. The end face of this sintered member is likewisemirror finished to be the surface roughness Ra=0.2 nm and the flatnessλ/2. The polished surfaces of both seed crystal and sintered member arerinsed using acetone for coupling by coating a mixed solution of BaCl₃and TiOCl₂ (mixing ratio thereof=1:0.5) on the coupling interface, andretained in the oxygen atmosphere at 1,370° C. for 50 hours, whilekeeping this state in the non-molten condition, for the execution ofsingle crystallization. After the growing process, the singlecrystallization takes place from the surface coupled with the seedcrystal to approximately 18 mm.

[0055] From this result, it has been found that the growing speed is0.36 mm/h, and that the growth is possible at a speed much faster thanthe growing speed of the conventional melt solidification method. Also,the ratio of pore content is 0.8 volume % in the single crystal ofBaTiO₃ of 93.0 mol %-PbTiO₃ of 7.0 mol %, which is obtained by thesintering method using the seed crystal, and the rearrangement densityis found to be 5×10²/cm² when examined by etching it in the HCl—HFsolution.

Third Embodiment

[0056] The BaTiO₃ series single crystal, which is manufactured by theTSSG method and made available on the market, is cut 5×5×0.5 mm on theorientation plane (100), and this plane is polished to be the surfaceroughness Ra=0.4 nm and the flatness λ/6. On the other hand, the BaTiO₃(Ba/Ti=0.9996) powder, which is manufactured by the hydrothermal method,and the PbTiO₃ (Pb/Ti=1.0000) powder, which is manufactured by thesolid-phase method, are blended in the ratio of 99.8 mol:0.2 mol. Whilebeing crushed by means of pot mill, this powder is formed into a disc(of 16 mm diameter), and sintered at 1,280° C. for three hours toproduce the sintered member having relative density of 98.9%. The molpercent of the elements contained in the sintered member thus obtained,with BaTiO₃ of 99.8 mol %-PbTiO₃ of 0.2 mol %, is (Ba+Pb)/Ti=0.9996, andthe average granular diameter of the crystal grain that constitutes thissintered member, having BaTiO₃ of 99.8 mol %-PbTiO₃ of 0.2 mol %, isapproximately 12 μm. The end face of this sintered member is mirrorfinished to be the surface roughness Ra=0.4 nm and the flatness λ/6. Thepolished surfaces of both seed crystal and sintered member are rinsedusing acetone for mechanical coupling, and retained in the oxygenatmosphere at 1,380° C. for 30 hours, while keeping this state in thenon-molten condition, for the execution of single crystallization. Afterthe growing process, the single crystallization takes place from thesurface coupled with the seed crystal to approximately 11 mm.

[0057] From this result, it has been found that the growing speed is0.37 mm/h, and that the growth is possible at a speed much faster thanthe growing speed of the conventional melt solidification method. Also,the ratio of pore content is 0.7 volume % in the single crystal ofBaTiO₃ of 99.8 mol %-PbTiO₃ of 0.2 mol %, which is obtained by thesintering method using the seed crystal, and the rearrangement densityis found to be 5×10³/cm² when examined by etching it in the HCl—HFsolution.

Fourth Embodiment

[0058] Single crystal growth is executed by the sintering method in thesame condition as that of the second embodiment. However, for thepresent embodiment, an electric furnace having an effective volume of150×150×150 mm, which is provided with molybdenum silicide heatgenerating member, is used. Then, 30 samples and 6 PZT sintered elementsof 20 mm diameter each are inserted into the furnace for growing in theatmosphere of 100% oxygen. After this process, all of the samples aresingle-crystallized up to almost 18 mm in length. The production speedis roughly estimated to be 108 cm³/furnace, because 30 samples of 16 mmdiameter×18 mm long each (volume, 3.6 cm³) are produced. The timerequired for the growth is 50 hours, which is 2.16 cm³ per hour.Therefore, the productivity is extremely high.

Fifth Embodiment

[0059] The BaTiO₃ (Ba/Ti=0.9973) powder, which is obtained by thesolid-phase method with 5-hour, provisional burning at 1,150° C. andcrushing, and the PbTiO₃ (Pb/Ti=1.0000) powder, which is prepared by wetmethod, are blended in a ratio of 75.0 mol and 25.0 mol, and formed intoa disc (of 30 mm diameter). The mol ratio of elements contained in thecompact power thus formed is (Ba+Pb)/Ti=0.9998. This compact powdermember is sintered at 1,320° C. for 50 hours to obtain the sinteredmember. The sintered member is composed of bulky crystal grain ofapproximately 1.10 mm diameter, and the composition of the sinteredmember is BaTiO₃ of 75.0 mol %-PbTiO₃ of 25.0 mol %. From this sinteredmember, the bulky crystal grain (single crystal) of BaTiO₃ of 75.0 mol%-PbTiO₃ of 25.0 mol % is drawn out.

[0060] The ratio of pore content is 3.2 volume % in the single crystalof the BaTiO₃ of 75.0 mol %-PbTiO₃ of 25.0 mol %. Also, therearrangement density thereof is examined by etching it in the HCl—HFsolution, with the result of 1×10²/cm², thus making the crystal defectsmall.

Sixth Embodiment

[0061] The BaTiO₃ (Ba/Ti=0.9973) powder and the PbTiO₃ (Pb/Ti=1.0000)powder, which are prepared by the same method as the fifth embodiment,are blended by wet method in a ratio of 75.0 mol and 25.0 mol, andformed into a disc (of 20 mm diameter). The mol ratio of elementscontained in the compact power thus formed is (Ba+Pb)/Ti=0.9998. Thiscompact powder member is sintered at 1,190° C. for five hours to obtainthe sintered member. The composition of this sintered member is BaTiO₃of 75.0 mol %-PbTiO₃ of 25.0 mol %, and the relative density is 97.8%.This sintered member is composed of crystal grain the average granulardiameter of which is approximately 10 μm. End face of this sinteredmember is processed to be the surface roughness Ra=0.2 nm, and theflatness λ/6. Then, the end face (100) of the BaTiO₃ series singlecrystal, which is prepared by the melt solidification method for use ofseed crystal, is processed in the same precision. Both polished faces ofthe sintered member and seed crystal are in contact and coupled at1,200° C. for 1 hour under a pressure of 9.8 MPa. With the sample thuscoupled, the sintered member of BaTiO₃ of 30.0 mol %-PbTiO₃ of 70.0 mol% is placed on a setter. With an MgO crucible being covered, the leadatmosphere is formed, and the single crystallization is executed at1,280° C. for 30 hours. After the growing process, the singlecrystallization is effectuated from the surface coupled with the seedcrystal to approximately 14 mm.

[0062] From this result, it has been found that the growing speed is0.47 mm/h, and that the growth is possible at a speed much faster thanthe growing speed of the conventional melt solidification method. Also,the ratio of pore content is 2.1 volume % in the single crystal ofBaTiO₃ of 75.0 mol %-PbTiO₃ of 25.0 mol %, which is obtained by thesintering method, and the rearrangement density is found to be 5×10²/cm²when examined by etching it in the HCl—HF solution, thus making crystaldefect small.

Seventh Embodiment

[0063] TiO₂ (26.6753 g), PbO (5.2080 g), and BaCO₃ (61.1742 g) are wetblended, and after dried, tentatively burned at 1,150° C. for fivehours, and, while being crushed, formed into a disc (of 20 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9980. This powder is sintered at 1,350° C. for10 hours to obtain the sintered member. The sintered member thusobtained is composed of bulky crystal grain of average granular diameterof approximately 3.0 mm. The composition of the sintered member isBaTiO₃ of 93.0 mol %-PbTiO₃ of 7.0 mol %. From this sintered member, thebulky crystal grain is drawn out as seed crystal, and the (110) plane ofthe crystal grain is cut out and finished with the surface roughnessRa=0.3 nm and the flatness λ/4. On the other hand, the same compound isformed into a disc of 10 mm diameter×20 mm thick, and sintered at 1,250°C. for three hours to obtain the sintered member of BaTiO₃ of 93.0 mol%-PbTiO₃ of 7.0 mol % in the relative density of 99.1%. The averagegranular diameter of the crystal grain that constitutes this sinteredmember is approximately 7 μm. The composition thereof is(Ba+Pb)/Ti=0.9980. The end face of this sintered member is mirrorfinished to be the surface roughness Ra=0.2 nm and the flatness λ/2. Thepolished surfaces of both seed crystal and sintered member are rinsedusing acetone for coupling by coating a mixed solution of BaCl₃ andTiOCl₂ (mixing ratio thereof=1:0.5) on the coupling interface. Each oneof sample and PZT sintered member are placed on a setter, and further,covered with an MgO crucible to form the atmosphere that contains Pb.While maintaining this state, these are retained at 1,370° C. for 20hours in the non-molten condition for the execution of singlecrystallization. After the growing process, the single crystallizationtakes place from the surface coupled with the single crystal toapproximately 18 mm.

[0064] From this result, it has been found that the growing speed is0.90 mm/h, and that the growth is possible at a speed faster than thegrowing speed indicated in the second embodiment. Also, the Pb densityof the surface layer of the sample of the single crystal of BaTiO₃ of93.0 mol %-PbTiO₃ of 7.0 mol %, which is obtained by the sinteringmethod, has almost no difference with the Pb density in the centralportion, and it has been found that the simple is composed uniformly asa whole. The ratio of pore content is 0.4 volume % in the single crystalof BaTiO₃ of 93.0 mol %-PbTiO₃ of 7.0 mol %, using the seed crystal, andthe rearrangement density is found to be 5×10²/cm² when examined byetching it in the HCl—HF solution.

Eighth Embodiment

[0065] The BaTiO₃ series single crystal, which is manufactured by theTSSG method and made available on the market as in the case of the thirdembodiment, is cut 5×5×0.5 mm on the orientation plane (111), and thisplane is polished to be the surface roughness Ra=0.3 nm and the flatnessλ/4 to make it seed crystal. On the other hand, the BaTiO₃(Ba/Ti=0.9993) powder, which is manufactured by the oxalate method, andthe PbTiO₃ (Pb/Ti=0.9960) powder, which is prepared by the solid-phasemethod are blended in the ratio of 93.2 mol:6.8 mol. While being crushedby means of pot mill, this powder is formed into a disc (of 16 mmdiameter), and sintered by means of hot press at 1,200° C. for 1 hour toproduce the sintered member having relative density of 99.4%. Thecomposition of the sintered member thus obtained is BaTiO₃ of 93.2 mol%-PbTiO₃ 6.8 mol %. The mol percent of the elements contained in thesintered member is (Ba+Pb)/Ti=0.9991. The sintered member is composed ofthe crystal grain the average granular diameter of which is,approximately 2 μm. The end face of this sintered member is mirrorfinished to be the surface roughness Ra=0.3 nm and the flatness λ/4. Thepolished surfaces of both seed crystal and sintered member are rinsedusing acetone for mechanical coupling. Each one of PZT sintered membercoupled with the sample is placed on a setter, and further, covered byan MgO crucible to form the atmosphere that contains Pb, and then,retained in the oxygen atmosphere at 1,370° C. for 20 hours, whilekeeping this state in the non-molten condition, for the execution ofsingle crystallization. After the growing process, the singlecrystallization takes place from the surface coupled with the seedcrystal to approximately 14 mm.

[0066] From this result, it has been found that the growing speed is0.70 mm/h, and that the growth is possible at a speed much faster thanthe growing speed of the conventional melt solidification method. Also,the ratio of pore content is 0.2 volume % in the single crystal ofBaTiO₃ of 93.2 mol %-PbTiO₃ of 6.8 mol %, which is obtained by thesintering method using the seed crystal, and the rearrangement densityis found to be 1 10³/cm² when examined by etching it in the HCl—HFsolution.

Ninth Embodiment

[0067] The BaTiO₃ series single crystal, which is manufactured by theTSSG method and made available on the market as in the third embodiment,is cut 5×5×0.5 mm on the orientation plane (100), and this plane ispolished to be the surface roughness Ra=0.3 nm and the flatness λ/4 tomake it seed crystal. On the other hand, the BaTiO₃ (Ba/Ti=0.9990)powder, which is manufactured by the oxalate method, and the PbTiO₃(Pb/Ti=0.9980) powder, which is manufactured by the solid-phase method,are blended in the ratio of 90.7 mol:9.3 mol. While being crushed bymeans of pot mill, this powder is formed into a disc (of 16 mmdiameter), and sintered at 1,200° C. for 1 hour O²—HIP (atmosphere: 20%O² and pressure: 98 MPa) to produce the sintered member of BaTiO₃ of90.7 mol %-PbTiO₃ of 9.3 mol %, the relative density of which is 99.96%.The sintered member thus obtained is composed of crystal grain ofaverage diameter of approximately 1 μm. The mol ratio of elementscontained in this sintered member is (Ba+Pb)/Ti=0.9989. The end face ofthis sintered member is mirror finished to be the surface roughnessRa=0.3 nm and the flatness λ/4. The polished surfaces of both seedcrystal and sintered member are rinsed using acetone for mechanicalcoupling. Each one of PZT sintered member coupled with the sample isplaced on a setter, and further, covered by an MgO crucible to form theatmosphere that contains Pb, and then, retained in the oxygen atmosphereat 1,370° C. for 19 hours, while keeping this state in the non-moltencondition, for the execution of single crystallization. After thegrowing process, the single crystallization takes place from the surfacecoupled with the seed crystal to approximately 18 mm.

[0068] From this result, it has been found that the growing speed is0.95 mm/h, and that the growth is possible at a speed much faster thanthe growing speed of the conventional melt solidification method. Also,the ratio of pore content is 0.0003 volume % in BaTiO₃—PbTiO₃ seriessingle crystal, which is obtained by the sintering method using the seedcrystal, and the rearrangement density is found to be 1×10³/cm² whenexamined by etching it in the HCl—HF solution.

Tenth Embodiment

[0069] The BaTiO₃ series single crystal, which is manufactured by theTSSG method and made available on the market as in the third embodiment,is cut 5×5×0.5 mm on the orientation plane (100), and this plane ispolished to be the surface roughness Ra=0.3 nm and the flatness λ/4 tomake it seed crystal. On the other hand, the BaTiO₃ (Ba/Ti=0.9945)powder, which is manufactured by the oxalate method, and the PbTiO₃(Pb/Ti=0.9952) powder, which is manufactured by the solid-phase method,are blended in the ratio of 55.0 mol:45.0 mol. While being crushed bymeans of pot mill, this powder is formed into a disc (of 16 mmdiameter), and sintered at 1,200° C. for 1 hour O²,—HIP (atmosphere: 20%O² and pressure: 98 MPa) to produce the sintered member of BaTiO₃ of55.0 mol %-PbTiO₃ of 45.0 mol %, the relative density of which is99.96%. The sintered member thus obtained is composed of crystal grainof average diameter of approximately 4 μm. The mol ratio of elementscontained in this sintered member is (Ba+Pb)/Ti=0.9948. The end face ofthis sintered member is mirror finished to be the surface roughnessRa=0.3 nm and the flatness λ/4. The polished surfaces of both seedcrystal and sintered member are rinsed using acetone for mechanicalcoupling. Each one of PZT sintered member coupled with the sample isplaced on a setter, and further, covered by an MgO crucible to form theatmosphere that contains Pb, and then, retained in the oxygen atmosphereat 1,360° C. for 20 hours, while keeping this state in the non-moltencondition, for the execution of single crystallization. After thegrowing process, the single crystallization takes place from the surfacecoupled with the seed crystal to approximately 13 mm. However, the ratioof pore content in the single crystal thus formed is 8.9 volume %, whichis in a condition of being too porous to be utilizable.

[0070] Based upon this result, the growing atmosphere is arranged with20% O²—80% Ar composition under 50 atmospheric pressure, and theaforesaid coupled sample of seed crystal—sintered member is retained at,1,350° C. for twenty-four hours for the heat treatment in the non-moltencondition. The sample, which has been processed under pressure, issingle-crystallized from the surface coupled with the seed crystal toapproximately 15 mm, and the growing speed is 0.63 mm/h. Thus, it hasbeen found that the growth is possible at a speed much faster than thegrowing speed of the conventional melt solidification method. Also, theratio of pore content is reduced to 5.1 volume % in the single crystalof BaTiO₃ of 55.0 mol %-PbTiO₃ of 45.0 mol %, which is obtained by thesintering method using the seed crystal, and the rearrangement densityis also found to be 1×10⁴/cm² when examined by etching it in the HCl—HFsolution.

Eleventh Embodiment

[0071] TiO₂ (26.7288 g), PbO (0.3720 g), and BaCO₃ (65.4498 g) are wetblended, and after dried, tentatively burned at 1,100° C. for fivehours, and, while being crushed, formed into a disc (of 20 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9960. This powder is sintered at 1,330° C. for10 hours to obtain the sintered member. The sintered member thusobtained is composed of bulky crystal grain of average granular diameterof approximately 2.6 mm. The composition of the sintered member isBaTiO₃ of 99.5 mol %-PbTiO₃ of 0.5 mol %. From this sintered member, thebulky crystal grain is drawn out as seed crystal, and the (001) plane ofthe crystal grain is cut out and finished with the surface roughnessRa=0.2 nm and the flatness λ/2. The electron beam diffraction image ofthis bulky crystal grain is measured. It is then confirmed that thesingle crystal has the crystalline orientation of extremely uniform.FIG. 5 shows this electron beam diffraction image. On the other hand,the same compound is formed into a disc of 10 mm diameter×20 mm thick,and sintered at 1,250° C. for three hours to obtain the sintered memberof BaTiO₃ of 99.5 mol %-PbTiO₃ of 0.5 mol % in the relative density of96.8%. The average granular diameter of the crystal grain thatconstitutes this sintered member is approximately 6 μm. The mol ratio ofelements contained in this sintered member is (Ba+Pb)/Ti=0.9960. The endface of this sintered member is likewise mirror finished to be thesurface roughness Ra=0.2 nm and the flatness λ/2. The polished surfacesof both seed crystal and sintered member are rinsed using acetone forcoupling by coating a mixed solution of BaCl₃ and TiOCl₂ (mixing ratiothereof=1:0.5) on the coupling interface, and retained in the oxygenatmosphere at 1,300° C. for 30 hours, while keeping this state in thenon-molten condition, for the execution of single crystallization. Afterthe growing process, the single crystallization takes place from thesurface coupled with the seed crystal to approximately 14 mm.

[0072] From this result, it has been found that the growing speed is0.47 mm/h, and that the growth is possible at a speed much faster thanthe growing speed of the conventional melt solidification method. Also,the ratio of pore content is 0.8 volume % in the single crystal ofBaTiO₃ of 99.5 mol %-PbTiO₃ of 0.5 mol %, which is obtained by thesintering method using the seed crystal, and the rearrangement densityis found to be 2×10²/cm² when examined by etching it in the HCl—HFsolution. FIG. 3 shows the result of measurement of the sample by meansof X-ray diffraction (before single crystallization), and FIG. 4 showsthe result thereof (after single crystallization). (In FIG. 4, two peeksare observable in the vicinity of 2θ=45°. This is because the X-ray oftarget own is separated into Kα₁ and Kα₂.)

Twelfth Embodiment

[0073] The BaTiO₃ series single crystal, which is manufactured by theTSSG method and made available on the market as in the third embodiment,is cut 5×5×0.5 mm on the orientation plane (001), and this plane ispolished to be the surface roughness Ra=0.3 nm and the flatness λ/4 tomake it seed crystal. On the other hand, the BaTiO₃ (Ba/Ti=0.9945)powder, which is manufactured by the oxalate method, and the PbTiO₃(Pb/Ti=0.9952) powder, which is manufactured by the solid-phase method,are blended in the ratio of 70.0 mol:30.0 mol. While being crushed bymeans of pot mill, this powder is formed into a disc (of 16 mmdiameter), and sintered at 1,200° C. for 1 hour O²—HIP (atmosphere: 20%O² and pressure: 98 MPa) to produce the sintered member of BaTiO₃ of70.0 mol %-PbTiO₃ of 30.0 mol %, the relative density of which is99.96%. The sintered member thus obtained is composed of crystal grainof average diameter of approximately 4 μm. The mol ratio of elementscontained in this sintered member is (Ba+Pb)/Ti=0.9947. The end face ofthis sintered member is mirror finished to be the surface roughnessRa=0.3 nm and the flatness λ/4. The polished surfaces of both seedcrystal and sintered member are rinsed using acetone for mechanicalcoupling. Each one of PZT sintered member coupled with the sample isplaced on a setter, and further, covered by an MgO crucible to form theatmosphere that contains Pb, and then, retained in the oxygen atmosphereat 1,330° C. for 20 hours, while keeping this state in the non-moltencondition, for the execution of single crystallization. After thegrowing process, the single crystallization takes place from the surfacecoupled with the seed crystal to approximately 12 mm. The ratio of porecontent is 3.8 volume % in the single crystal thus formed. Therearrangement density is found to be 7×10³/cm² when examined by etchingthe sample in the HCl—HF solution.

Thirteenth Embodiment

[0074] TiO₂ (26.6246 g), PbO (3.7200 g), and BaCO₃ (62.4898 g) are wetblended, and after dried, tentatively burned at 1,100° C. for fivehours, and, while being crushed, formed into a disc (of 20 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9999. This powder is sintered at 1,300° C. for10 hours to obtain the sintered member. The sintered member thusobtained is composed of bulky crystal grain of average granular diameterof approximately 2.2 mm. The composition of the sintered member isBaTiO₃ of 95.0 mol %-PbTiO₃ of 5.0 mol %. From this sintered member, thebulky crystal grain is drawn out as seed crystal, and the (111) plane ofthe crystal grain is cut out and finished with the surface roughnessRa=0.3 nm and the flatness λ/4. On the other hand, the same compound isformed into a disc of 10 mm diameter×20 mm thick, and sintered at 1,250°C. for three hours to obtain the sintered member of BaTiO₃ of 95.0 mol%-PbTiO₃ of 5.0 mol % in the relative density of 98.4%. The averagegranular diameter of the crystal grain that constitutes this sinteredmember is approximately 5 μm. The mol ratio of elements contained inthis sintered member is (Ba+Pb)/Ti=0.9999. The end face of this sinteredmember is mirror finished to be the surface roughness Ra=0.3 nm and theflatness λ/4. The polished surfaces of both seed crystal and sinteredmember are rinsed using acetone for coupling by coating a mixed solutionof BaCl₃ and TiOCl₂ (mixing ratio thereof=1:0.5) on the couplinginterface. While maintaining this state, these are retained at 1,350° C.for 20 hours in the non-molten condition for the execution of singlecrystallization. After the growing process, the single crystallizationtakes place from the surface coupled with the single crystal toapproximately 12 mm.

[0075] From this result, it has been found that the growing speed is0.60 mm/h, and that the growth is possible at a speed faster than thegrowing speed of the conventional melt-solidification method. Also, theratio of pore content is 0.5 volume % in the single crystal of BaTiO₃ of95.0 mol %-PbTiO₃ of 5.0 mol %, which is obtained by the sintered methodusing the seed crystal, and the rearrangement density is found to be5×10²/cm² when examined by etching it in the HCl—HF solution.

Fourteenth Embodiment

[0076] TiO₂ (26.8908 g), PbO (3.7200 g), and BaCO₃ (62.4898 g) are wetblended, and after dried, tentatively burned at 1,100° C. for fivehours, and, while being crushed, formed into a disc (of 20 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9990. This powder is sintered at 1,300° C. for10 hours to obtain the sintered member. The sintered member thusobtained is composed of bulky crystal grain of average granular diameterof approximately 2.8 mm. The composition of the sintered member isBaTiO₃ of 95.0 mol %-PbTiO₃ of 5.0 mol %. From this sintered member, thebulky crystal grain is drawn out as seed crystal, and the (001) plane ofthe crystal grain is cut out and finished with the surface roughnessRa=0.3 nm and the flatness λ/4. On the other hand, the same compound isformed into a disc of 10 mm diameter×20 mm thick, and sintered at 1,250°C. for three hours to obtain the sintered member of BaTiO₃ of 95.0 mol%-PbTiO₃ of 5.0 mol % in the relative density of 98.7%. The averagegranular diameter of the crystal grain that constitutes this sinteredmember is approximately 6 μm. The mol ratio of elements contained inthis sintered member is (Ba+Pb)/Ti=0.9990. The end face of this sinteredmember is mirror finished to be the surface roughness Ra=0.3 nm and theflatness λ/4. The polished surfaces of both seed crystal and sinteredmember are rinsed using acetone for coupling by coating a mixed solutionof BaCl₃ and TiOCl₂ (mixing ratio thereof=1:0.5) on the couplinginterface. While maintaining this state, these are retained at 1,350° C.for 30 hours in the non-molten condition for the execution of singlecrystallization. After the growing process, the single crystallizationtakes place from the surface coupled with the single crystal toapproximately 7 mm.

[0077] From this result, it has been found that the growing speed is0.23 mm/h, and that the growth is possible at a speed faster than thegrowing speed of the conventional melt-solidification method. Also, theratio of pore content is 0.6 volume % in the single crystal of BaTiO₃ of95.0 mol %-PbTiO₃ of 5.0 mol %, which is obtained by the sintered methodusing the seed crystal, and the rearrangement density is found to be1×10⁴/cm² when examined by etching it in the HCl—HF solution.

Fifteenth Embodiment

[0078] BaTiO₃ (Ba/Ti=0.9954) powder, PbTiO₃ (Pb/Ti=1.0000) powder, andCaTiO₃ (Ca/Ti=1.0000) powder, which are manufactured by wet method, arewet blended in a mol ration of 70.0:29.0:1.0 in that order, and formedinto a disc (of 20 mm diameter). For the compact powder member thusformed, the mol ratio of contained elements is (Ba+Pb)/Ti=0.9868. Thispowder is sintered at 1,350° C. for 10 hours to obtain the sinteredmember. The sintered member thus obtained is composed of bulky crystalgrain of average granular diameter of approximately 3.3 mm. Thecomposition of the sintered member is BaTiO₃ of 70.0 mol %-PbTiO₃ of29.0 mol %-CaTiO₃ of 1.0 mol %. From this sintered member, the bulkycrystal grain is drawn out as seed crystal, and the (001) plane of thecrystal grain is cut out and finished with the surface roughness Ra=0.3nm and the flatness λ/4. On the other hand, the same compound is formedinto a disc of 10 mm diameter×20 mm thick, and sintered at 1,250° C. forthree hours to obtain the sintered member of BaTiO₃ of 70.0 mol %-PbTiO₃of 29.0 mol %-CaTiO₃ of 1.0 mol % in the relative density of 98.9%. Theaverage granular diameter of the crystal grain that constitutes thissintered member is approximately 6 μm. The mol ratio of elementscontained in this sintered member is (Ba+Pb)/Ti=0.9868. The end face ofthis sintered member is mirror finished to be the surface roughnessRa=0.3 nm and the flatness λ/4. The polished surfaces of both seedcrystal and sintered member are rinsed using acetone, and then, coupledat 1,200° C. for one hour under a pressure of 9.8 MPa. The PZT sinteredmember is placed on a setter together with the coupled sample, andcovered with an MgO crucible to form the lead atmosphere for the singlecrystallization at 1,350° C. for 50 hours. After the growing process,the single crystallization takes place from the surface coupled with thesingle crystal to approximately 11 mm.

[0079] From this result, it has been found that the growing speed is0.22 mm/h. The ratio of pore content is 4.1 volume % in the singlecrystal of BaTiO₃ of 70.0 mol %-PbTiO₃ of 29.0 mol %-CaTiO₃ of 1.0 mol′% which is obtained by the sintered method. Also, the rearrangementdensity is found to be 1×10⁴/cm² when examined by etching it in theHCl—HF solution.

FIRST COMPARATIVE EXAMPLE

[0080] TiO₂ (27.1652 g), PbO (3.7200 g), and BaCO₃ (62.4898 g) are wetblended, and after dried, tentatively burned at 1,110° C. for fivehours, and, while being crushed, formed into a disc (of 16 mm diameter).For the compact powder member thus formed, the mol ratio of containedelements is (Ba+Pb)/Ti=0.9800. This powder is sintered at 1,350° C. for30 hours to obtain the sintered member of BaTiO₃ of 95.0 mol %-PbTiO₃ of5.0 mol %. The sintered member thus obtained is composed of crystalgrain of average granular diameter of only 50 μm. Therefore, the sameprocess as the third embodiment is given to the (100) plane of theBaTiO₃ series single crystal, which is grown by the TSSG method and madeavailable on the market, to make it the seed crystal. On the other hand,the same compound is formed into a disc of 10 mm diameter×10 mm thick,and sintered at 1,250° C. for three hours to obtain the sintered memberof BaTiO₃ of 95.0 mol %-PbTiO₃ of 5.0 mol % in the relative density of98.1%. The average granular diameter of the crystal grain thatconstitutes this sintered member is approximately 12 μm. The mol ratioof elements contained in this sintered member is (Ba+Pb)/Ti=0.9800. Theend face of this sintered member is mirror finished to be the surfaceroughness Ra=0.4 nm and the flatness λ/6 as in the third embodiment. Thepolished surfaces of both seed crystal and sintered member are rinsedusing acetone for coupling by coating a solution of HNO₃ of 2N on thecoupling interface. While maintaining this state, these are retained at1,370° C. for 50 hours in the non-molten condition for the execution ofsingle crystallization.

[0081] After the single crystal growing process, the singlecrystallization takes place from the surface coupled with the singlecrystal only to 100 μm. It is found from this result that the growingspeed is 2×10⁻³ mm/h, that almost no single crystallization hasadvanced.

SECOND COMPARATIVE EXAMPLE

[0082] BaTiO₃ (Ba/Ti=1.0000) and PbTiO₃ (Pb/Ti=1.0100) powder isprepared by the coprecipitation method, and blended in a ration of 90.0mol:10.0 mol. While being crashed by means of hot mill, this blendedpowder is formed into a disc (of 16 mm diameter). For the compact powdermember thus formed, the mol ratio of contained elements is(Ba+Pb)/Ti=1.0010. This powder is sintered at 1,350° C. for 10 hours toobtain the sintered member of BaTiO₃ of 90.0 mol %-PbTiO₃ of 10.0 mol %.The sintered member thus obtained is composed of minute crystal grain ofaverage granular diameter of approximately 3 μm, thus making itimpossible to obtain the single crystal in a size sufficient enough tobe used as seed crystal. Therefore, as in the case of the firstcomparative example, the BaTiO₃ series single crystal, which is grown bymeans of the TSSG method and made available on the market, is used asthe seed crystal. On the other hand the same compound is formed into adisc of 10 mm diameter×15 mm thick, and sintered at 1,250° C. for threehours to obtain the sintered member of BaTiO₃ of 90.0 mol %-PbTiO₃ of10.0 mol % in the relative density of 97.8%. The mol ratio of elementscontained in this sintered member is (Ba+Pb)/Ti=1.0010. The end face ofthis sintered member is mirror finished to be the surface roughnessRa=0.4 nm and the flatness λ/6 as in the first comparative example. Thepolished surfaces of both seed crystal and sintered member are rinsedusing acetone for coupling by coating a mixed solution of BaCl₃ andTiOCl₂ (mixing ratio: 1:1) on the coupling interface. While maintainingthis state, these are retained at 1,390° C. for 30 hours in thenon-molten condition for the execution of single crystallization. Afterthis growing process, it is found that almost no single crystallizationhas taken place, but only in a width of approximately 1 to 2 grain(approximately 5 to 10 μm) from the surface coupled with the seedcrystal.

THIRD COMPARATIVE EXAMPLE

[0083] BaTiO₃—PbTiO₃ series single crystal is grown by means of the TSSGmethod. As the material of solution, the BaTiO₃ powder, TiO₂ powder, andPbTiO₃ powder, which are available on the market, are used. The sinteredmember is prepared using the material powder in a mol ratio ofBaTiO₃:TiO₂:PbTiO₃=1:0.5:0.01. This sintered member is placed in aplatinum crucible to melt the material by means of high-frequencyinduction heating. The growing temperature is 1,440° C. The BaTiO₃ seedcrystal of <100> orientation, which is fixed to the platinum holer, isimmersed in this solution, and the temperature is decreased at 0.4° C./halong with the rotation of 30 rpm, and the crystallization is performedby a speed of 0.1 mm/h. After approximately 200 hours, the drawing-upterminates when the temperature reaches 1,330° C. (eutectoidtemperature). The crystal thus obtained is 25 mm diameter and 16 mm long(volume: 7.9 cm³). the inside of the crystal is of porous structure (theratio of pore content: 8 volume %) having many numbers of voids ofseveral μm to several tens of μm created along with the Pb evaporationon the way of growth. With a microscope, the occurrence of manyinclusions other than perovskite phase is observed. The rearrangementdensity in the crystal is 2×10⁶/cm². It is larger than the rearrangementdensity of the BaTiO₃—PbTiO₃ series single crystal of the presentinvention. Also, the productivity is only 0.04 cm³/h, which isapproximately {fraction (1/100)} as compared with the productivity ofthe BaTiO₃—PbTiO₃ series single crystal of the present invention.

[0084] As regards each of the embodiments described above, the Table 1shows the various piezoelectric properties of the BaTiO₃—PbTiO₃ seriessingle crystal manufactured particularly in the first, second, and sixembodiments, the general PZT sintered member, the BaTiO₃ sintered memberand BaTiO₃ series single crystal grown by means of the TSSG method,respectively. TABLE 1 Comparison of Specific Characteristics between thePresent Invention and the Conventional Art Fist Second Sixth ComperativeComperative Embodiment Embodiment Embodiment Example Example BaTiO₃ of99.0 BaTiO₃ of 93.0 BaTiO₃ of 75.0 Comperative BaTiO₃ BaTiO₃ mol%-PbTiO₃ of mol %-PbTiO₃ of mol %-PbTiO₃ Example Series Series 1.0 mol %Single 7.0 mol % Single of 25.0 mol % PZT Sintered Sintered SingleSample Crystal Crystal Single Crystal Member Member Crystal CurieTemperature (° C.) 125 155 246 290 120 120 Permittivity afterPolarization 3900 2700 1500 300 3000 4700 Dielectric Loss (%) 0.30 0.280.19 1.9 2.5 0.25 Coupling Coefficient k₃₃ (%) 86 89 91 71 48 85Piezoelectric Constant d₃₃ (pC/N) 520 580 620 290 118 500 Amount ofInduced Distortion (%) 0.92 1.25 1.69 0.11 0.06 0.90 Field 30 (kV · cm)

[0085] Next, with reference to FIGS. 1A and 1B, the description will bemade of a piezoelectric type actuator (piezoelectric oscillator) usingthe BaTiO₃—PbTiO₃ series single crystal of the present invention, and aliquid discharge head using such piezoelectric type actuator. The liquiddischarge head 11 shown in FIG. 1A and FIG. 1B is provided with aplurality of discharge ports 12; the liquid chamber 13 which is arrangedcorresponding to each discharge port 12; and the piezoelectric typeactuator 19 which is arranged for each liquid chamber 13, respectively.The piezoelectric type actuator 19 comprises the piezoelectric member 14that includes at least the layer formed by BaTiO₃—PbTiO₃ series singlecrystal; electrodes (not shown) of Pt, Au, Al, or the like formed on thesurface of the piezoelectric member 14; and the oscillating plate 17that is bonded with the piezoelectric member 14, thus forming apiezoelectric oscillator. Each liquid discharge port 12 for the liquiddischarge head 11 is formed for a nozzle plate 15 at specific intervals.Each liquid chamber 13 is formed on the base plate portion 16 inparallel to each liquid discharge port 12 correspondingly. Each of theliquid discharge ports 12 and the corresponding liquid chamber 13 areconnected through the liquid flow path 16 a formed for the base plateportion 16, respectively. Also, on the upper face of the base plateportion 16, each opening portion 16 b is formed corresponding to each ofthe liquid chambers 13, and on the upper face of base plate portion 16,the oscillating plate 17 is formed to cover each opening portion 16 b.On this oscillating plate 17, the piezoelectric member 14 is arranged tobe positioned corresponding to each liquid chamber 13.

[0086] For the liquid discharge head 11 structured described above, thepiezoelectric type actuator 19 is driven to press liquid in thecorresponding liquid chamber 13 when driving signals are applied fromoutside to the piezoelectric type actuator 19, and liquid is dischargedas liquid droplet from the liquid discharge port 12 communicated withthe liquid chamber 13.

[0087] With the BaTiO₃—PbTiO₃ series single crystal, which is apiezoelectric material having a small amount of lead content therein,and used as the piezoelectric member (piezoelectric oscillator) thatconstitutes such piezoelectric type actuator, it becomes possible toobtain excellent piezoelectric properties at lower costs in much bettercondition than the PZT properties conventionally available. Further, itbecomes possible to manufacture the environment-friendly piezoelectrictype actuator (piezoelectric oscillator), and the liquid discharge headas well.

1. BaTiO₃—PbTiO₃ series single crystal single-crystallized by heatingBaTiO₃—PbTiO₃ compact powder member or sintered member having a smallerPb-containing mol number than Ba-containing mol number, while keepingsaid powder or member in non-molten condition.
 2. BaTiO₃—PbTiO₃ seriessingle crystal according to claim 1, wherein the rearrangement densityis 10² pieces/cm² or more and 10⁶ pieces/cm² or less, and the ratio ofpore content is within a range of 1 volume ppm or more and 5 volume % orless.
 3. BaTiO₃—PbTiO₃ series single crystal according to claim 1,wherein the ratio of PbTiO₃ content is 45 mol % or less. 4.BaTiO₃—PbTiO₃ series single crystal according to claim 3, wherein theratio of PbTiO₃ content is 30 mol % or less.
 5. BaTiO₃—PbTiO₃ seriessingle crystal according to claim 4, wherein the ratio of PbTiO₃ contentis 25 mol % or less.
 6. BaTiO₃—PbTiO₃ series single crystal according toclaim 1, wherein the volume of said single crystal is 1 mm³ or more. 7.A piezoelectric type actuator comprising: a layer formed byBaTiO₃—PbTiO₃ series single crystal according to claim
 1. 8. A liquiddischarge head comprising: the piezoelectric type actuator according toclaim
 7. 9. BaTiO₃—PbTiO₃ series single crystal having the rearrangementdensity of 10² pieces/cm² or more and 10⁶ pieces/cm² or less, and theratio of pore content being within in a range of 1 volume ppm or moreand 5 volume % or less.
 10. BaTiO₃—PbTiO₃ series single crystalaccording to claim 9, wherein the ratio of PbTiO₃ content is 45 mol % orless.
 11. A piezoelectric type actuator comprising: a layer formed byBaTiO₃—PbTiO₃ series single crystal according to claim
 9. 12. A liquiddischarge head comprising: the piezoelectric type actuator according toclaim
 11. 13-24. (Cancelled)